Recently, buildings are often seen subjected to heat insulation treatment in order to decrease cost of air-conditioning of the buildings and generation of carbon dioxide from the air-conditioning. Since it is hard, in view of costs or other aspects, to provide walls or roofs with a new structure, it is often found that the wall or roof is subjected, on the surface, to application of a heat insulation paint (including those which are able to selectively reflect infrared light).
The heat insulation paint generally mixes hollow members such as glass, shirasu, etc., of a low heat transfer coefficient. The inside of the hollow members is air or to be almost vacuum. And the hollow member itself, which is very much small (10-600 μm), is substantially not broken.
Furthermore, the roof or wall surface of the buildings are naturally exposed to the outside air and mostly get dirty and stained with dust, smokes, etc. When the surface of roofs or walls get dirty and stained, reflectivity of the light lowers, so that the roof or wall is likely to absorb heat, resulting in lowering of the heat insulation effect.
To this situation, it is known to mix in to the paint a photo-catalyst which is able to prevent pollution or decompose polluted substances and cause them to be flowed with rain. Catalyzing function of the photo-catalyst facilitates that any organic substances, etc., adhered on the surface of roof or wall are decomposed, and dispersed into the air or washed away.
Also, a combination of the hollow member and the photo-catalyst is disclosed in the patent document 1 in which fine or minute particles of photo-catalyst are stuck on the surface of the hollow members.
Patent document 1: Japanese Unexamined patent application No. HEI 11-009965.
However, for the invention of the patent document 1, since the photo-catalyst oxidizes and decomposes organic substances, there is a need to take special arrangements to this function when the invention is applied to organic paints. But, there is not at all found such special arrangements in the patent. In addition, the photo-catalyst is stuck to the hollow members by use of an ordinary bonding adhesive. But, there is no consideration of oxidative decomposition of the bonding adhesive. Thus, it is doubtful to practically use the invention of the patent document 1.